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Published October 1, 2012 | Published + Submitted
Journal Article Open

Dissipationless dynamics of randomly coupled spins at high temperatures

Abstract

We develop a technique to compute the high-frequency asymptotics of spin correlators in weakly interacting disordered spin systems. We show that the dynamical spin correlator decreases exponentially at high frequencies ⟨SS⟩_ω ∼ exp(−τ∗ω) and compute the characteristic time τ∗ of this dependence. In a typical random configuration, some fraction of spins form strongly coupled pairs, which behave as two-level systems. Their switching dynamics is driven by the high-frequency noise from the surrounding spins, resulting in low-frequency 1/f noise in the magnetic susceptibility and other physical quantities. We discuss application of these results to the problem of susceptibility and flux noise in superconducting circuits at mK temperatures.

Additional Information

© 2012 American Physical Society. Received 1 February 2012; published 15 October 2012. We are grateful to R. McDermott for the discussion of the experimental situation. This work was supported, in part, by Triangle de la physique 2007-36, ANR-06-BLAN-0218, ECS-0608842, ARO W911-09-1-0395, DARPA HR0011-09-1-0009. A.K. acknowledges funding by the Institute of Quantum Information under NSF Grant No. PHY-0803371.

Attached Files

Published - PhysRevB.86.134414.pdf

Submitted - 1112.3855v1.pdf

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